Intervalometer



May 28, 1957 M. H. BALLER ET AL 2,794,079

INTERVALOMETER Filed July 29, 1955 '1 2: l5 .2 {HHMMFI E ii l7 :E 25INVENTORS MAURICE H. BALLER ROBERT K. BOLE FIG.6 HERBERT STONE a/IMHATTORNEYS INTERVALOMETER Maurice H. Baller, Washington, D. C., Robert K.Bole, Bethesda, Md., and Herbert Stone, Washington, D. C.,

; assignors to the United States of America as represented by theSecretary of the Navy Application July 29, 1955, Serial No. 525,404

3 Claims. (Cl. 200-) (Granted under Title 35, U. S. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

This invention relates to an intervalorneter and more particularly to animprovement in intervalometers of the drum contact selector switch typeof the nature disclosed in application Serial No. 337,255, filedFebruary 16, 1953, by Robert K. Bole and Maurice H. Baller.

The present invention has been designed primarily for regulating thefiring order of an array of shipboard projectiles, commonly known ashedgehogs, such that the projectiles may be activated in any desiredsequence and at non-uniform intervals of time between successiveinitiating pulses. To insure a simultaneous deposit of all theprojectiles on a relatively large target area, the missiles, which mustbe launched to various ranges of the target area, are required to befired at different time intervals. Sequence switches are normallyemployed for controlling the firing order of the projectiles to achievea simultaneous blanket coverage of the target area. Knownintervalometers adapted for use in the environment of hedgehogprojectile firing have operated on the principle of uniform timeintervals between activating pulses. This principle is inherentlydisadvantageous since a regular rhythm of vibration which may damage themissile launching equipment is created.

An object of the present invention is to provide an intervalometer forinitiating the activation of a plurality of projectiles in any desiredsequence.

Another object is the provision of an intervalometer for initiating theactivation of a plurality of projectiles in any desired sequence and atnon-uniform intervals of time between successive initiating pulses toprevent launching vibrational forces from becoming accumulative.

Another object is to provide an intervalometer designed to fire an arrayof projectiles on shipboard at non-uniform intervals in such order thatthey will arrive at the target area at the same time and in a pattern ofdistribution that will blanket a submerged target.

A further object is to provide a conductive 'drum assembly with aplurality of contactor points circumferentially and longitudinallyspaced on the drum to afford a desired sequence of pulses at non-uniformintervals of time between the successive pulses.

Still another object is the provision of a sequence switch of theconductive rotative drum type having replaceable insulating rings slipmounted on the drum to carry electrical contacts.

A further object is to provide an intervalometer having stationary brushcontacts which are cammed into electrical engagement with the rotatingcontacts in a manner which aids in keeping the contacts engaged whileundergoing shock, and extends the life of the brush contacts.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the followes t ing detailed description when considered inconnection with the accompanying drawings wherein:

Fig. 1 which shows a plan view partly broken away of a preferredemobdiment of the present invention;

Fig. 2 illustrates a side elevation of the apparatus shown in Fig. 1;

Fig. 3 is an end view of the preferred embodiment shown in Fig. 2;

Fig. 4 shows a section of the device taken substantially along line 4-4of Fig. 1 looking in the direction of the arrows;

Fig. 5 illustrates in detail a drum contact and its associated recessedring seating; and

Fig. 6 is a fragmentary perspective view of the cam portion of theinsulating ring.

Referring now to the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views,there is shown in Fig. l, a shaft 10 which is intended to be motordriven at a constant speed, and which may be hand driven on occasion, bymeans not shown, as, for example, when the necessity for contactchecking arises. The shaft 10 carries a conductive drum 11 of suitablematerial such as metal on which is slip mounted a series of rings 12 ofinsulating material. Each ring 12 is of stepped cross-sectional contourconsisting of a high peripheral portion 13 and a low peripheral portion14, the ultimate drum contour resulting from the assembly of the ringson the drum producing a succession of grooves 15. Each of .the groovesis occupied by a contact leaf spring 16 which is held by an insulatorbar 17 in fixed relationship to the revolvable drum 11 normal to theaxis of shaft 10. As best shown in Fig. 5, each of the rings 12 have arecess formed on one face 18 of the high peripheral portion 13, whichrecess extends into the low peripheral portion 14. The composite recessaccommodates a J-shaped contact 19, illustrated in Fig. 5, which is heldin fixed position by a screw 21 which passes through a smooth hole inthe ring 12 and is driven into a tapped hole 22 in the drum 11. Thescrew 21 thus serves to secure the contact to the ring, to secure thecontact and ring to the drum, and to provide electrical continuitybetween the drum and the contact.

In securing the ring 12 to the drum 11 the screw 21 also functions tolocate the ring 12 both angularly an d longitudinally on the drum 11. Acam 23 on ring 12 is located approximately diametrically oppositecontact 19 on the ring face 24 opposite that face on which contact 19 ispositioned. Each of the cams 23 of rings 12 are of the same size incircumferential extent and each are in the same angular relationshipwith the respective recesses in face 18 of the rings. It can be readilyappreciated that any program of activation of the contacts 19 may beestablished by the relative positioning of the contacts with each otheron the conductive drum 11. In other words, orientation of the contacts19 on the drum 11 is made in such a manner that either uniform ornonuniform time intervals may exist between activation of the numerouscontacts 19.

Leaf spring contact brushes 16, shown best in Figs. 2 and 3, are fixedlymounted on insulator bar 17 by a threaded member 25 which passes througha hole provided in the insulator bar 17. Shake-proof soldering lugs 28are by means of the threaded coupling member 25 held in superjacentrelationship with' the tang of the contact brush 16. Shims 29 are placedbetween the tang26 of leaf spring contact brush 16 and the metal bushing27 and held in position by the threaded coupling member 25 to provide afine adjustment of the point of engagement of the spring 16 with thecontact 19. By removing or adding shims 29 from beneath the tang 25 ofthe brush 16 the point of engagement between the spring and the contactmay be set either forward or back War thus setting the time for contactbetween brush 16 and contact 19 to a precise point and allowing exactnon-uniform timing to be made between contacts.

The cam 23 of one ring 12 is adapted to depress the spring brush 16 ofthe ring 12 next to it. As the cam advances .on the spring, the campasses leaf portion .31 of spring brush'16 and the next adjacent ringsurface without making engagement, but when the cam reaches the curvedterminal 32 of the brush, which extends below :the normal plane ofthespring 16 and into the path of the cam 23, lateral deflection of thespring occurs with the result that a convolution 33 of spring 16 isforced into brushing engagement with the contact 19.

The mode of actuating the spring 16 against the con tact 19 has theadvantage of leaving the spring brush relaxed when the drum 11 isat'rest-and during the time the drum is revolving withthe. cam 23disengaged from brush 16. Spring deflection is therefore reserved forthe moment of making contact and thereby wear on the spring 16 and thering 12 is reduced. Further, when spring brush 16 is contained betweenthe cam 23 and the contact 19, it is positively held against the contacteven under moderate conditions of shock.

The operation of the invention can be understood by visualizing an arrayof projectiles set up in horizontal rows for firing. The object is toset off the projectiles in such order that they will arrive at thetarget area at the same time and in a pattern of distribution that willblanket the submerged target vessel. It is easy to see that since theprojectiles'are set up in close order and that from there they mustspread out over the near, 'far, side ind intermediate reaches of anenormously enlarged target pattern, it becomes necessary to project themissiles to various ranges by projection at various angles of elevationor by other means. Projecting the missiles to various ranges from apoint which is essentially fixed in spaced results in trajectories withvarious flight times, and in nonuniform increments of change betweensuccessive flight times.

Therefore, the contacts 19 will be staggered on the drums, some closetogether, others farther apart in the circumferential direction as shownin Fig. 1. The distribution of the contacts 19 .is so arranged thatfiring will occur at non-uniform intervals, the character of the 11011-uniformity being tailored to fire the projectiles for the far,intermediate, and near trajectories at the proper time. The program offiring or activation of the contacts 19 can be arranged so as to firethe projectiles in accordance with any desired target pattern. A timingsequence for firing the projectiles at various ranges is predetermined,and holes 22 are tapped into drum 11 to correspond with this sequence.The insulating rings 12 are then mounted on the drum, and screws 19 fixthe contacts 19 and-rings 12 into position. Contact brushes 16 arethenstationed by means. of insulator bars 17 and shims 29 into assembly withdrum 11, and electrical continuity is thereby completed from drum 11through contacts 19 to brush contacts 16, and from the brushcontacts 16through cou-. pling member 25 to lugs 28 to which areconnected'electrical leads.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. An intervalometer comprising a rotatable electrically conductivedrum, a plurality of insulating rings of stepped cross-sectional contourstacked on the drum in side-by-side relationship to form a series ofannular grooves on the periphery of the drum, drum contacts car ried bythe rings on the face thereof which forms one side of the annulargrooves and extending across the portion of said rings forming thebottom of the grooves, said rings each being provided with a "passagecommunieating the drum with the drum contacts, cam surfaces located onsaid rings diametrically opposite the drum contacts and on the otherface of said rings which forms the other side of the annular grooves,electrically conductive fastening means positioned on said ringsconnecting the drum contacts to the conductive drum via the passagesprovided through. said rings at the portion forming the bottom of thegrooves,;and brush means fixedlypositioned about the periphery of saiddrum'and extending into the grooves thereon, said brush means beingbiased into engagement with-the drum contacts by said cam surfaces.

2. An intervalometer comprising a rotatable electrically conductivedrum, aplurality of insulating rings of stepped cross-sectionalcontourstacked onpthe drum in side-bys'ide relationship to form a series ofannular grooves on the peripheryof the drum, drum contacts carried bythe rings on the face thereof which forms one side of the annulargrooves and extending across the portion of said rings forming thebottom of the grooves, said rings each being provided witha passagecommunicating the drum with the drum contacts, cam surfaces located onsaid rings diametrically opposite the drum contacts andon the o'therface of said rings which forms the other side of the annular grooves,electrically conductive fastening means positioned onsaid ringsconnectingtthe drum contacts to the conductive 'drum via the passagesprovided. through saidrings at the portion forming the bottom of thegrooves, and leaf spring contact brushes fixedly positionedabout theperiphery of the drum and extending into the insulating grooves on saiddrum, said'brushes normally being engaged by the cam surfaces of therings to contact the drum contacts.

3. An intervalometer comprising a rotatable electrically conductivedrum, a plurality of insulating rings of stepped cross-sectional contourstacked on the drum in side-byside relationship to form a series ofannular grooves on the periphery of the drum, drum contacts carried bythe rings on the face thereof which forms one side of the annulargrooves and extending across the portion of said ring forming the bottomof the grooves, cam surfaces located on said rings diametricallyopposite the drum contacts and onthe other face of said rings whichforms the other side of the annular grooves, electrically conductivefastening means positioned on said rings connecting the drum contacts tothe conductive drumvia passages provided through said rings at theportion forming the bottom of the grooves, insulator bars laterally andcircumferentially spaced about said drum with their axes parallel to theaxis of the drum, leaf spring contact brushes held by each of theinsulator bars and extending into the insulating grooves -on the drum,and means provided on said bars to adjust the extension of the brushesinto the grooves, said brushes being engaged by the cam surfaces of therings to contact the drum contacts.

References Cited in the'file of this patent UNITED STATES PATENTS

